# Many Plum Neuralizer ## Description Integrated OBD-II to UART Interface Board — Updated Project Description and Verification Plan ## Project Details - **Owner:** ryanf - **Created:** 10/7/2025 - **Last Updated:** 10/7/2025 - **Visibility:** Public - **PowerBudget_ActionPlan:** Gather maximum supply current (worst-case) numbers from datasheets for U1 (STN2120), U2 (MCP2562), U3 (TJA1050), U4 (NCV7356), U5 (MIC5021), U6 (MCP1416), U7 (TPS56624x quiescent), U8 (LM317KCS), U9 (LM317KCS) and any other power-consuming parts; compute total worst-case current per rail (3.3V rail, J1850 rail, 5V rail); apply ≥30% headroom to each rail; calculate LM317 dissipation = (Vin - Vout) * I_total for U8 (3.3V) and U9 (J1850); obtain LM317KCS thermal resistance (θJA) from LM317KCS datasheet and compute temperature rise = dissipation * θJA at assumed ambient 25°C; compare to LM317 maximum junction temperature to verify margin; if junction temp > allowed, list required thermal mitigation (heatsink, copper area, or change regulator). - **PowerBudget_Status:** pending_datasheet_fetch - **System Architecture Diagram:** ```mermaid flowchart TB Vehicle_DB9["DB9 Vehicle Connector"] --> Input_Protection["Input Protection & ESD Clamps"] Input_Protection --> Power_In["5V Buck (TPS56624x)"] Power_In --> Reg_3V3["LM317 3.3V Regulator"] Power_In --> Reg_J1850["LM317 J1850 Adjustable Regulator"] Reg_3V3 --> STN2120["STN2120 OBD-II Protocol IC"] Reg_3V3 --> CAN_HS["High-Speed CAN Transceiver"] Reg_3V3 --> CAN_MS["Medium-Speed CAN Transceiver"] Reg_3V3 --> CAN_SW["Single-Wire CAN Transceiver"] Reg_3V3 --> ISO_KL["K/L Line Driver (MOSFET/BJT)"] Reg_J1850 --> J1850_DRV["J1850 VPW/PWM Driver (MOSFET/BJT)"] STN2120 --> UART_Header["UART Header (100Ω series resistors)"] CAN_HS -->|120Ω term & RC filter (100Ω+560pF)| DB9_CAN_HS["DB9 CAN_HS pins"] CAN_MS -->|120Ω term & RC filter (100Ω+560pF)| DB9_CAN_MS["DB9 CAN_MS pins"] CAN_SW -->|120Ω term & RC filter (100Ω+560pF)| DB9_CAN_SW["DB9 CAN_SW pins"] ISO_KL -->|K-Line| DB9_K["DB9 K-Line pin"] ISO_KL -->|L-Line| DB9_L["DB9 L-Line pin"] J1850_DRV -->|VPW/PWM| DB9_J1850["DB9 J1850 pin"] ``` ## Key Components ### D1 — [SZNUP2125WTT3G](https://www.flux.ai/lcsc/sznup2125wtt3g~uqey.md) - Role: Protection - Manufacturer Part Number: SZNUP2125WTT3G - JLCPCB Part Class: Extended Part - Manufacturer Name: onsemi(安森美) - Product Info Url: https://lcsc.com/product-detail/TVS_ON-Semicon-ON-SZNUP2125WTT3G_C457791.html - Role Details: ESD/TVS clamp for interface lines - Package or Case Code: SC-70-3_L2.1-W1.3-P1.30-LS2.1-BR - Datasheet URL: https://storage.googleapis.com/graviton-electric-symbols/document_assets/lcsc/1912111437_onsemi-SZNUP2125WTT3G_C457791.pdf - LCSC Part Number: C457791 - Part Type: TVS **Pins:** - 1 [pin 1] - 2 [pin 2] - 3 [pin 3] ### J1 — [DB9_Female_MountingHoles](https://www.flux.ai/adrian95/db9femalemountingholes~9m8.md) - Role: Connector - Part Type: Connector - Role Details: OBD-II vehicle interface **Pins:** - 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - PAD ### J2 — [Pin Header 01x06 2.54mm Vertical](https://www.flux.ai/vasy_skral/pin-header-01x06-254mm-vertical~jyw.md) - Role: Connector - Part Type: Connector - Role Details: UART header TX/RX - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - Pin_1 [pin 1] - Pin_2 [pin 2] - Pin_3 [pin 3] - Pin_4 [pin 4] - Pin_5 [pin 5] - Pin_6 [pin 6] ### U1 — STN2120 - Role: Integrated Circuit - Manufacturer Part Number: STN2120-I/ML - Datasheet URL: https://www.scantool.net/scantool/downloads/206/stn21xx_ds_c.pdf - Part Type: Integrated Circuit - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: OBD-II protocol interface - Manufacturer Name: OBD Solutions **Pins:** - !ISO_K_TX/GP6 [pin 43] - !ISO_L_TX/GP7 [pin 44] - !ISO_RX/GP5 [pin 21] - !J1850_BUS+_VH¯/GP4 [pin 25] - !LED_HOST_ACT/GP24 [pin 13] - !LED_OBD_ACT/!RST_NVM/GP22 [pin 12] - !PWR_CTRL /GP19 [pin 32] - !RESET [pin 18] - !SLEEP/GP18 [pin 27] - ANALOG_IN [pin 19] - AVDD [pin 17] - AVSS [pin 16] - GP28 [pin 1] - GP29 [pin 2] - GP30 [pin 3] - GP31 [pin 15] - GP32 [pin 20] - GP33 [pin 26] - GP34 [pin 37] - GP35 [pin 38] - HS_CAN_RX/GP8 [pin 10] - HS_CAN_TX/GP9 [pin 8] - J1850_BUS-_TX/GP3 [pin 33] - J1850_BUS+_TX/GP2 [pin 24] - LED_STATUS/GP26 [pin 14] - MS_CAN_RX/GP10 [pin 11] - MS_CAN_TX/GP11 [pin 9] - OSC1 [pin 30] - OSC2 [pin 31] - PAD [pin 45] - PWM_RX/GP0 [pin 23] - SW_CAN_LOAD/GP16 [pin 34] - SW_CAN_MODE0/GP14 [pin 35] - SW_CAN_MODE1/GP15 [pin 36] - SW_CAN_RX/GP12 [pin 42] - SW_CAN_TX/GP13 [pin 41] - UART_RX [pin 5] - UART_TX [pin 4] - VCAP [pin 7] - VDD [pin 40] - VDD [pin 28] - VPW_RX/GP1 [pin 22] - VSS [pin 39] - VSS [pin 6] - VSS [pin 29] ### U2 — [MCP2562-E-SN](https://www.flux.ai/kicad-part-library/mcp2562-e-sn~ed.md) - Manufacturer Part Number: MCP2562-E-SN - Manufacturer Name: Microchip Technology Inc. - Package or Case Code: SOIC-8_3.9x4.9mm_P1.27mm - Role: Interface - Datasheet URL: http://ww1.microchip.com/downloads/en/DeviceDoc/25167A.pdf - Role Details: HS-CAN transceiver **Pins:** - CANH [pin 7] - CANL [pin 6] - RXD [pin 4] - STBY [pin 8] - TXD [pin 1] - VDD [pin 3] - Vio [pin 5] - VSS [pin 2] ### U3 — [TJA1050T/CM,118](https://www.flux.ai/vasyl/tja1050tcmc118~k8r.md) - Datasheet URL: https://cz.mouser.com/datasheet/2/302/TJA1050-3083416.pdf - Role: Interface - Manufacturer Name: NXP Semiconductors - Part Type: CAN transceiver - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: TJA1050T/CM,118 - Role Details: MS-CAN transceiver **Pins:** - CANH [pin 7] - CANL [pin 6] - GND [pin 2] - RXD [pin 4] - S [pin 8] - TXD [pin 1] - VCC [pin 3] - VREF [pin 5] ### U4 — [NCV7356D1R2G](https://www.flux.ai/vasyl/ncv7356d1r2g~1m.md) - Manufacturer Part Number: NCV7356D1R2G - Role Details: SW-CAN transceiver - Role: Interface - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Name: onsemi - Part Type: Interface - Datasheet URL: https://www.onsemi.com/pdf/datasheet/ncv7356-d.pdf **Pins:** - CANH [pin 7] - GND [pin 8] - LOAD [pin 6] - MODE0 [pin 2] - MODE1 [pin 3] - RXD [pin 4] - TXD [pin 1] - VBAT [pin 5] ### U5 — MIC5021YM - Role Details: ISO9141/14230 (K/L) line driver - Manufacturer Name: Microchip Technology Inc. - Manufacturer Part Number: MIC5021YM - Role: Driver - Package or Case Code: SOIC127P600X170-9N - Compliance: RoHS - Part Type: High-side MOSFET driver - Datasheet URL: https://ww1.microchip.com/downloads/en/DeviceDoc/MIC5021.pdf - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - CT [pin 3] - GATE [pin 7] - GND [pin 4] - INPUT [pin 2] - SENSE- [pin 6] - SENSE+ [pin 5] - VBOOST [pin 8] - VDD [pin 1] ### U6 — [MCP1416](https://www.flux.ai/kicad-part-library/mcp1416~2q0.md) - Manufacturer Name: Microchip Technology Inc. - Package or Case Code: SOT-23-5 - Manufacturer Part Number: MCP1416 - Role: Driver - Datasheet URL: http://ww1.microchip.com/downloads/en/DeviceDoc/20002092F.pdf - Role Details: J1850 VPW/PWM driver **Pins:** - GND [pin 4] - IN [pin 3] - NC [pin 1] - OUT [pin 5] - Vdd [pin 2] ### U7 — TPS56624x - Datasheet URL: https://www.ti.com/product/TPS562242 - Manufacturer Part Number: TPS566242 - License: https://creativecommons.org/licenses/by/4.0/ - Role Details: 5 V buck converter - Manufacturer Name: Texas Instruments - Role: Power Management - Part Type: Integrated Circuit **Pins:** - AGND [pin 4] - EN [pin 5] - FB [pin 6] - GND [pin 3] - SW [pin 2] - VIN [pin 1] ### U8 — [LM317KCS](https://www.flux.ai/jecstronic/lm317kcs~e0s.md) - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: LM317KCS - Role Details: 3.3 V adjustable linear regulator - Datasheet URL: https://www.ti.com/lit/ds/symlink/lm317.pdf - Manufacturer Name: Texas Instruments - Part Type: Integrated Circuit - Role: Power Management **Pins:** - ADJUST [pin 1] - INPUT [pin 3] - OUTPUT [pin 2] ### U9 — [LM317KCS](https://www.flux.ai/jecstronic/lm317kcs~e0s.md) - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: LM317KCS - Datasheet URL: https://www.ti.com/lit/ds/symlink/lm317.pdf - Role Details: J1850 adjustable linear regulator - Role: Power Management - Manufacturer Name: Texas Instruments - Part Type: Integrated Circuit **Pins:** - ADJUST [pin 1] - INPUT [pin 3] - OUTPUT [pin 2] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/ryanf/many-plum-neuralizer~tal](https://www.flux.ai/ryanf/many-plum-neuralizer~tal).* --- *Generated from [https://www.flux.ai/ryanf/many-plum-neuralizer~tal](https://www.flux.ai/ryanf/many-plum-neuralizer~tal)*